The word "theory" is confusing me lately re scientific investigation. Is a scientific theory put forth before, after, or before and after a scientific investigation conducted according to the scientific method? Include the role of an hypothesis in your answer.
a hypothesis is an idea that has not been tested thoroughly. a theory is an idea that has been tested and not been shown to be wrong by any tests. a law is an idea that has been very thoroughly tested, has stood the test of time, and is generally accepted as the only reasonable theory.
the scientific method, in the form that you typically find it in middle school texts at least, is an idealized system that cannot always be used. many ideas (especially in astronomy, ecology, or geolgy for example) cannot be tested by the commonly put forth "scientific method".
I considered your answers, and it seems to me that a theory, unless a law, stands on shaky legs, although scientists insist on the reliability of the scientific method. Interesting in the link is the admission that a theory must also be falsifiable. In summary, we are in big trouble when a law is falsifiable.
From an article written by John Rennie in the July 2002 Scientific American comes the following:
Many people learned in elementary school that a theory falls in the middle of a hierarchy of certainty--above a mere hyopthesis but below a law. Scientists do hot use the terms that way, however. According to the National Academy of Sciences (NAS), a scientific theory is "a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses." No amount af amount of validation changes a theory into a law, which is a descriptive generalization about nature. So when scientists talk about the theory of evolution--or the atomic theory or the theory of realitivity, for that matter--they are not expressing reservations about its truth.
In addition to the theory of evolution, meaning the idea of descent with modification, one may also speak of the fact of evolution. The NAS describes a fact as "an observation that has been repeatedly confirmed and for all practicle purposes is accepted as "true."
Any theory OR LAW of science may fall if contradictory evidence is discovered. In fact, if a theory is not falsifiable, it is not a scientific theory. It is a metaphysical statement.
Examples:
A scientific hypothesis: Cancer is caused by a virus. The reason this is a scientific hypothesis is that it may some day be disproved by research. As in Redi's experiment, it may someday be proved that cancers can develop in the absence of any virus or any history of contact with viruses. Science can't do that now, because viruses are 'everywhere' and are incredibly tiny, so it can't be excluded that a cancer tumor was exposed to one, once. But it is disprovable, in the future.
An unscientific hypothesis, or metaphysical statement: A gudger is an invisible being, without any detectable energy, it is tasteless, odorless, has no weight or mass, makes no sound, and furthermore, it detests instruments, so if approached by any scientific measurement equipment, it instantly disappears into another dimension. Challenge: design an experiment to detect the gudger. Hypothesis: Gudgers exist. How do you design an experiment which proves that gudgers do not exist? Even in the future? Since it is not falsifiable, it is not a scientific hypothesis/theory. That does not mean, however, that many people will not believe that gudgers exist.
Newton's laws of motion (or, as he called them, principles of motion) made sense out of what people had observed about the earth, the planets, the sun, the moon and the stars. For thousands of years, astrologers had wanted to understand these motions, because their predictions depended on an exact understanding. But they had been unable to explain.
But Newton's Laws were shown to be incomplete in the last century.
Scientists know they still do not have the whole picture. What they want is one single theory which will explain gravity, the force that holds the particles of the nucleus together, the force that acts between charges and magnets, and the force that acts in certain subatomic decay processes. If they succeed, Newton's Laws will be dead as a dodo, except in practical applications to suitable problems.
Posts: 6256 | Location: British Columbia, Canada | Registered: 06-11-02
i think that there was a little misunderstanding of the term "falsifiable" earlier in this thread. falsifiable means that sometestcan be performed that wouldbe expected to fail if the theory was false. for instance, God's existence cannot be a scientific theory because no one can come up with a test that would be expected to fail if god doesn't exist.
methos5000: Correcting my answer above, I meant that we are in big trouble when a law is shown to be false. My use of the word "falsifiable" for a law was incorrect. The word "falsifiable" applies to a theory.
There is no real distinction between a scientific law and a scientific theory. Newton's laws of motions are theories. All scientific laws and theories are falsifiable.
Only metaphysical theories are not falsifiable.
If I have a theory that an invisible non-material being resides in my garden shed, it is not falsifiable. That is because no test can prove whether the being is there or not.
Posts: 6256 | Location: British Columbia, Canada | Registered: 06-11-02
